/*
 * Copyright 2022 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.kie.internal.services;

import java.util.HashMap;
import java.util.Map;
import java.util.ServiceLoader;

public abstract class AbstractMultiService<K, V> {

    private volatile Map<K, V> servicesMap;

    protected V getService(K key) {
        if (servicesMap == null) {
            init();
        }
        return servicesMap.get(key);
    }

    private synchronized void init() {
        if (servicesMap == null) {
            servicesMap = new HashMap<>();
            ServiceLoader<V> loader = ServiceLoader.load(serviceClass());
            for (V service : loader) {
                servicesMap.put(serviceKey(service), service);
            }
        }
    }

    protected abstract Class<V> serviceClass();

    protected abstract K serviceKey(V service);
}
